1.What is sonar and how does it work?

2. Pixels. Why are they so important?

3. Fish arches. Now you see them, now you don't. Why?

What is sonar and how does it work?

Greatly simplified, a sonar unit is just a combination of a speaker, microphone and stopwatch. Every fish finder "knows" that the speed of sound through water is about 4,800 feet per second. It transmits a sound pulse and then measures the time it takes for echoes to return from the pulse. Then it converts the elapsed time for each echo into distance. A built-in computer organizes all of this information and shows it on a display screen.